SIPs house in Toowoomba

Bill and Margaret Curnow’s house in Toowoomba is built using structural insulated panels and is being monitored for heating and cooling energy use by QUT. Dr Wendy Miller reports on the research.

MOST Australian homes are built using timber or steel frames, over which internal and external wall linings and a roof are then added, along with insulation between these ‘skins’. Structural insulated panels (SIPs) present a whole new construction technique: these panels provide the linings, insulation and structural framework all in one unit.

My research team at Queensland University of Technology (QUT) has been examining how houses using SIPs are actually performing, in terms of comfort and energy use (i.e. heating and cooling impacts), as well as how the homeowners and their designers and builders have managed this new construction method. This research is part of an Australian Research Council project looking at how innovation and high energy performance can be implemented in Australia’s housing industry. Bill Curnow’s house in Toowoomba is one of four SIPs homes in our research. The other homes are located in South Australia, Victoria and Western Australia. Our project also examines performance of homes that have implemented other innovations.

Temperature performance

Toowoomba is in a warm temperature climate zone that tends to require more heating than cooling in houses. There are six months of the year where the mean minimum temperature is less than 13 °C and only two months where the mean maximum temperature is higher than 27 °C. Despite this, temperature extremes as high as 40 °C and as low as -3 °C (or -16.5 °C with wind chill factor!) can occur. Houses should be able to provide some level of occupant comfort under ‘normal’ as well as extreme weather conditions.

We compared the outdoor temperatures for Toowoomba with temperatures in Bill’s living room. In January 2016, Toowoomba’s outdoor temperatures ranged from 19 °C to 34.2 °C, with a mean of 28 °C. In July, the outdoor temperature ranged from 10.8 °C to 24.5 °C, with a mean of 17.5 °C (interestingly, almost 1 °C hotter than the long-term mean for this month).

Compare this with the much more comfortable range of temperatures in Bill’s living room, as shown in Table 1, with January temperatures largely in the range 20 °C to 26 °C and July temperatures in the range 15 °C to 21 °C. This performance with no additional space heating or cooling suggests that the living room is performing equivalent to an 8.5 to 9 Star rating.